A digital scanning microscope usually makes a digital image of a sample such as a tissue sample placed in a microscope slide. This is typically done by scanning the sample over the whole microscope slide and stitching different image spans together and/or by overlaying images measured at different wavelengths. FIG. 1 schematically represents a cross-section 100 of such a microscope slide. A glass slide 101, a cover slip 102 and a mounting medium 103 for fixing and sealing off a sample 104, like e.g. a biological tissue layer, are comprised. It is known, for example, from WO 2001/084209, that digital scanning microscopes can comprise a 2D line sensor, also known as a line scan camera or as a linear array sensor. Such sensors comprise only one line, said differently one row, of sensing pixels. It is also known that compared to other types of sensors, like 2D array sensors, for example, 1D line sensors are able to provide better continuous mechanical scanning operation, less stitching problems, and can allow for the use of so-called time delay integration (TDI) line sensors.
Furthermore, current imaging sensor designs provide photoactive pixels which consist of photosensitive parts, i.e. photodiodes, and also comprise non-photosensitive parts like a plurality of charge to voltage converters (CVC) that are embedded in the pixel itself leading to a lower fill factor. This means that the pixel typically has three transistors (rolling shutter) of four transistors (global shutter) for the CVC and both vertical and horizontal metal lines for addressing and read out are needed. However, such non-photosensitive parts of the pixel reduce the fill factor of the pixel which is especially harming during low light conditions. The resulting low light sensitivity of pixels in a conventional sensor is typically overcome by applying microlenses. Such microlenses try to effectively focus less amount of light onto the pixels of the imaging sensor such that the collateral loses are minimized. In addition, currently available imaging sensors provide for a relative low speed in reading out the region of interest (ROI) as only a limited number of read out electronics can be provided within the limited space of a given pixel size.